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Last Updated June 6, 2024

Program Overview


Regulatory Policy



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In August 2007, Illinois enacted legislation (S.B. 680) requiring the Illinois Commerce Commission (ICC) to establish standards for net metering and interconnection for renewable energy systems by April 1, 2008. Although S.B. 680 only requires the promulgation of interconnection standards for "eligible renewable generating equipment," the ICC chose to take this opportunity to develop standards for all distributed generation up to 10 megawatts (MW). Final interconnection standards were adopted by the ICC in August 2008. In March 2010, the ICC established interconnection standards for Large Distributed Generation Facilities, or those over 10 MW. In December 2016, the ICC made changes to the interconnection rules.

Interconnection of Distributed Generation Facilities (up to 10 MW)

The interconnection rules set four levels of review for interconnection requests. A project must meet all of the requirements of a given classification in order to be eligible for that level of expedited review. The level of review required is generally based on system capacity, whether system components are certified by a nationally recognized testing laboratory (NRTL), and whether the system is connected to a radial distribution circuit or to an area network. The basic definitions* for each tier are as follows:

  • Level 1: Certified, inverter-based systems with a capacity rating of 10 kilowatts (kW) or less (25 kW under 2016 changes).
  • Level 2: Varies based on voltage of line at point of interconnection (500 kW or less for lines less than 5 kV, 3 MW or less for lines of 5-14.99 kV, 4MW or less for lines of 15-29.99 kV, and 5 MW or less for lines between 30 and 68.99 kV).
  • Level 3: Certified systems with a capacity rating of 50 kW or less connected to an area network and from which power will not be exported; or certified, non-power-exporting systems with a capacity rating of 10 MVA (megavolt-amperes) or less connected to a radial distribution network.
  • Level 4: Systems with a capacity of 10 MVA or less that do not meet the criteria for inclusion in a lower tier, including all systems using non-certified components and those that require additional construction by the utility in order accommodate the facility.

The 2016 changes removed a provision of the earlier rule requiring that interconnection projects (under levels 1, 2, and 3) require no new construction from the utility in order to receive expedited review. Under the new rules, these interconnections can still receive expedited review so long as they require only "Minor System Modifications."

The ICC adopted IEEE 1547 as the technical standard of evaluation in July 2007. Systems are considered to be lab-certified if the components have been evaluated as compliant with UL 1741 and the 2008 National Electric Code (NEC) according to the testing protocols of IEEE 1547. The rules also specify the technical screens which may be applied to applications at each level of review as well as time limits for different stages of the evaluation process. Generally speaking, higher level applications are subject to more intensive screening and longer time limits.

All systems are required to have an external disconnect switch directly accessible to the utility. Facilities larger than 1 MW must carry liability insurance with coverage of at least $2 million per occurrence and $4 million in aggregate. Standardized interconnection agreements are available for all four tiers. The Tier 1 agreement is a simplified version of that used for projects requiring higher levels of review.

Interconnection of Large Distributed Generation Facilities (10 MW or larger)

The ICC adopted a separate set of rules applicable to distributed generation facilities over 10 Megawatts, which are not covered under the above interconnection standards. These rules provide a standard set of procedures covering the interconnection process as well as standard agreements. It should be noted that interconnections covered by the Federal Energy Regulatory Commission (FERC), the Midwest Independent Transmission System Operator, or PJM Interconnection are not subject to these new rules. See this page for more information.

* The definitions here cover several important classification criteria; however, interested parties should consult the actual rule for more precise definitions and additional restrictions.